August 16, 2011

Breaking down intelligence to environmental and genetic components

Razib has an interesting post in which he argues that as living conditions become good for most members of a society, the environmental component of intelligence should diminish, and the genetic one should increase.

The basic idea could be expressed as follows: give the exact same amount of water, sunlight, nutrients, etc. to two different trees, and the amount of fruit they will produce will depend entirely on their genes.

Likewise, make sure every kid has food, clean water, a home, medical care, schooling, etc. and then their differences in intelligence will depend entirely on their genes.

Hence:

A perfect meritocracy would replace cultural class with biological caste.

It's a seductive argument, that overlooks, I think, an important factor:

Different organisms have different optimal environments for their best performance.

Let's go back to the tree analogy. If you equalize their environments, then their output (fruit) will depend entirely on their genetic input (genes). But what environment should be chosen?

A desert plant is ruined by too much water, a jungle one by too little.

It is far from an obvious proposition that the "ideal environment" as currently envisioned by Western social policy makers is indeed the optimal one for all members of our species.

A Norwegian and a Nigerian will both suffer if they are exposed to the sun too much or too little, but their optimal "sun exposure" points are different; a Pygmy and an Eskimo will die of starvation with too little food and of a variety of ailments with too much, but their optimal "daily colorie intake" points are different. Even members of the same population differ in what is good for them.

In Aristotelian terminology, "mean is best", but "mean" is not the same for all, and what is an excess for one is a deficiency for another.

It could be argued that current affluent societies do not enforce particular environments, but give the freedom to their members to choose their own. In a truly affluent society where anyone has the means to adopt whatever lifestyle is best for them, it will be the case that variation in any particular trait (e.g., intelligence) will depend on one's genes: Norwegians, Nigerians, Pygmies, and Eskimos may choose what is good for them, they are not forced to live in a suboptimal environment

That, however, is a mixed blessing because a free society is also a very particular kind of society that is not necessarily best for all. It could very well be that some organisms reach their optimum performance under compulsion, and I see no reason to think that kids (or adults) become excellent by doing what they want and not by following the instructions of those who know better.

For example, kids learn to read and do multiplications by being forced to do a lot of tedious repetition. In a free society, an adult is largely free from compulsion, but that does not mean that he will choose to do what is best for himself.

In a free and affluent society everyone has the potential of having the best possible physique and the best possible cognitive ability that their genotype will allow: "money is no object." But, as we well know, few people use their freedom to achieve their full potential.

In conclusion:

Fix the genes (as in clones or identical twins) and all variation is due to the environment

Fix the environment and all variation is due to genes

The eugenicist's dream is to "improve the genes" -- but "better genes" for what environment?

The social engineer's dream is to "improve the environment" -- but "better environment" for which genetic natures?

8 comments:

That, however, is a mixed blessing because a free society is also a very particular kind of society that is not necessarily best for all.

The most well known ancient equivalents of free and non-free societies are Athens and Sparta respectively and they had similar levels of power. Likewise, we see similar levels of power in the democratic USA and Britain, the Nazi Germany, the communist USSR and, increasingly, the communist China, despite the very significant differences in the levels of freedom between these countries. There is no single recipe for success. My favorite recipe is meritocratic aristocracy, but even it may not succeed in every environment, as factors like average intelligence (which is very largely genetic) of the society are very important too.

It could be argued that current affluent societies do not enforce particular environments, but give the freedom to their members to choose their own.

The general process where an individual chooses a specific environment (or ecological strategy) based on what his/her genes have provided in a body has been called “matching habitat choice”. [Edelaar et al. 2008] This process applies to both social and non-social populations, and not just those with high intelligence, either. It may turn out to be a critical factor in how evolution works, especially among the higher primates where they can come up with inventive strategies to overcome obstacles provided by their bodies, as well as take advantage of opportunities.

That, however, is a mixed blessing because a free society is also a very particular kind of society that is not necessarily best for all. It could very well be that some organisms reach their optimum performance under compulsion, and I see no reason to think that kids (or adults) become excellent by doing what they want and not by following the instructions of those who know better.

This might also be true of people whose primary strategy is compelling others. A society that gives them scope for that behavior might allow them to prosper much more than they would in a society that prohibited them.

As a matter of theory, Dienekes is right. As a matter of empirical evidence, Razib has the better case.

The empirical evidence shows that the lower one's socio-economic status, the weaker the relative role of IQ.

Put another way, genes appear to determine peak IQ potential, not actual IQ, which is more of a gene-environment mix. There are many known environmental deprivations that suppress IQ. But, in the absence of those deprivations, in the real world, the heritability of IQ is high and more importantly, beyond "good enough" the proportion of IQ attributable to genes remains pretty stable. Very good envirnomental circumstances relative to "good enough" circumstances seem to only have a very slight IQ enhancing effect.

IQ doesn't directly translate into socio-economic class although it is one important factor. Extraversion and conscientiousness personality traits, for example, have material impacts on socio-economic class, and there is a healthy dose of luck and access of family economic resources and connections apart from who you are as a person that come into play. Bill Gates would not have become rich if someone with exactly the same genes and family resources had he been born in 1915.

We may not have biological caste. There is too much randomness afoot for that. But, the longer you have a meritocracy and assortive mating the more tempting it is for society to impose caste culturally since the overlap is so large.

Peak IQ potential is determined by genes, given a particular environment.

It could very well be that a genotype A always expresses a higher IQ than a genotype B.

Or, that A expresses a higher IQ than B in a range of environments, and B higher than A in a different range of environments.

And, it may be that A and B express the same IQ in their optimal environments, or that A expresses a higher IQ in A's optimal environment than B does in _his_ optimal environment.

I would also add that we currently know almost nothing about what environmental factors cause high IQ (except trivia like food, water, shelter, health care etc.), nor do we know what the physiological limit of our brains is; it is far from obvious that the best current specimens of our species represent the upper limit, or that the upper echelons of today's society have an optimal environment for creating high IQs (more on this soon).

There is no such thing as ONE homogeneous "environment". There is also something called the "economic environment" and Niches will persist.

It might not look it, but the scheme of environment vs. genes is simplistic. Not only because there is more to it than these two factors (i.e. the economic environment and environmental heterogeneity) but also because even on a binary level environment/genes are a feedback loop.

Group wise, a change in environment will simply alter the frequency of traits within a population as a population will now respond adaptively, and hence change the group make up, not eliminate the group.

On free society. The notions as outlined are anti-democratic. Both you and this Pakistani don't know enough about Democracy to comment, as you both come from un-democratic regimes. You merely offer your own caricature of "free society" which would be typical of a Greeka and a Pakistani. I say this without any disrespect. You have to be aware of your own biases.

You could suggest (rightly) that different diets suit different individuals; say, one individual will have an optimum IQ outcome with a grain-free flesh/fish based diet and another on a diet high in whole grains and sugary fruits. Different educational styles could also be valid.

So really, it's anyone with a biology compatible with the culture they live in that will fare well. You'd assume a thriving ethnic group's culture would at least have a rough 'best fit' with it's average citizens 'best outcome' requirements. Which would end up with a meritocracy having a strongly genetic component. Possibly it's an argument against immigration (for the immigrants sake). It might by why immigrant groups have higher levels of mental health problems: their optimum environment (diet, etc) might be just a different enough to cause problems.

The results from a series of follow-up studies indicate that the IQ score at age 13 could be viewed as a relatively good indicator for future life outcomes, defined in terms of attained education, occupational status, and material well being. Dramatic differences in this attainment between the groups of respondents with high and low IQ scores attest to this conclusion. Smaller, yet still significant, differences between talented teenagers and their counterparts from the two control groups who apparently did not have the high IQ advantage also support the thesis that IQ matters much for life success.

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